Heretofore, various fitting methods that involve getting a golfer to take practice hits with test clubs, measuring the action with a measurement device, and selecting a golf club suited to the golfer based on the measurement values have been proposed. As one of these methods, JP 2013-226375A (hereinafter, Patent Literature 1) discloses a fitting method for selecting a shaft of a golf club suited to a golfer. Specifically, in Patent Literature 1, first, the flexural stiffness of a shaft suited to a golfer is determined based on measurement values obtained with a test club. Then, shafts matching the value of the flexural stiffness are extracted from among a large number of shafts registered in a database. This method shows great promise as a technique that improves the fitting precision of shafts.